The present invention relates to a structure for supporting a diaphragm spring employed in a friction clutch for an automobile or the like.
A conventional friction clutch basically has a structure as shown in FIG. 1. In FIG. 1, a frictional facing 3 is positioned between a flywheel 1 of an engine and an annular pressure plate 2. The facing 3 is fixed to an outer peripheral portion of a clutch disc 5 connected to an output shaft 4 (only a center line thereof is illustrated). When the pressure plate 2 presses the facing 3 onto the flywheel 1, the clutch engages and a torque is transmitted from the flywheel 1 through the disc 5 to the output shaft 4. A diaphragm spring 6 for forcing the pressure plate 2 toward the facing 3 is disposed at the rear of the pressure plate 2 opposite to the disc 5. The outer peripheral portion of the spring 6 is seated on a projection 7 on the rear surface of the pressure plate 2. When the inner peripheral portion of the spring 6 is pushed by a release bearing 8 toward the disc 5, the spring 6 elastically deforms into a shape shown by phantom line 6a and releases the force against the pressure plate 2, so that the clutch disengages.
The outer periphery and the rear surface of the spring 6 are covered by a clutch cover 10. The clutch cover 10 includes a substantially annular end wall 11 and a cylindrical peripheral wall 12 which inclines and projects from the outer periphery of the end wall 11 toward the flywheel 1 and is fixed at the end thereof to the flywheel 1. Circumferentially spaced axial pins 13 are fixed at their ends to the inner peripheral portion of the wend wall 11. The pins 13 extend from the end wall 11 through recesses 15 of the spring 6 toward the pressure plate 2, and are provided at the other ends with enlarged ends 14 positioning between the pressure plate 2 and the spring 6, respectively.
As shown in FIG. 2, which is a fragmentary schematic sectional view taken along line II--II in FIG. 1, the recesses 15 or slits extend radiately from the inner periphery to the radially middle portion of the spring 6. Thus, the outer peripheral portion of the spring 6 forms a continuous annular portion 16, and the portion radially inside the annular portion 16 is divided by the recesses 15 to form divided lever portions 17. Said pins 13 extend through the radially outer portions of the recesses 15 adjacent to the annular portion 16.
A pair of wire rings 19 and 20 are disposed outside, in the radial direction of the spring 6, of the pins 13. The pins 13 are employed to support the radially inner peripheries of the wire rings 19 and 20. The wire rings 19 and 20 form fulcrums for the spring 6. One wire ring 19 is disposed between the spring 6 and the wall 11. The second wire ring 20 is disposed between the spring 6 and the ends 14 of the pins 13.
In the clutch, sliding occurs at parts pressed between the wire rings 19, 20 and the spring 6, clutch cover 10 and pins 13, when the clutch is operated for engagement and disengagement. However, in the conventional clutch, the wire rings 19 and 20 are made only from steel. Seizure may occur between the parts pressed together. Such seizure increases frictional forces, and thus, a clutch pedal can not be operated smoothly and lightly.
Further, in the conventional clutch, since vibration of the engine transmitted from the flywheel 1 to the clutch cover 10 is directly transmitted through the wire rings 19 and 20 and the spring 6 to the clutch operation mechanism such as the clutch pedal, the driver may feel uncomfortable.
Accordingly, it is an object of the invention to provide an improved structure, overcoming the above-noted problems, in which structures of wire rings for diaphragm spring are improved.
According to the invention, a structure for supporting a diaphragm spring in a clutch comprises a pressure plate; a clutch cover covering the rear of the pressure plate; a diaphragm spring disposed between the pressure plate and the clutch cover for forcing the pressure plate and provided with recesses radiately extending from the inner periphery of the spring; support means extending from the inner periphery of the clutch cover through radially outer portions of the recesses; and a pair of wire rings employed as fulcrums for said spring and supported by said support means; at least a part of surfaces of said wire rings being formed by solid lubricant material having a small coefficient of friction and contacting at least one of the clutch cover, the diaphragm spring and the support means.
Other objects, features and advantages of the invention will appear more fully from the following description of the preferred embodiments of the invention.